Clinical Relevance of Bacteria Identified using MALDI – TOF Technology
Abstract: Recent technological advances in clinical microbiology have revolutionized bacterial identification. Mass spectrometry methodology is replacing traditional biochemical methods to identify bacteria and yeasts isolated from human infections. MALDI-TOF (Matrix Assisted Laser Desorption Ionization Time of Flight) measures protein profiles and masses of disrupted microbial cells and compares them to a database of known organism profiles. This allows for very accurate identification to species level very rapidly and with minimal sample preparation.
MALDI-TOF technology has been quickly adopted as the gold standard for bacterial identification so the question of accuracy is not a significant issue. Future endeavors will focus upon interpretation and reporting by clinical microbiologists of the sometimes unfamiliar bacterial genera and species detected.
We evaluated patient isolates previously identified by MALDI-TOF methodology by performing identification using currently available automated biochemical methodology technology and other manual methods. Discordant results were evaluated to determine clinical relevance of the isolates and the potential for alterations in antimicrobial therapy.
Our results provide examples in which current automated systems may be unable to identify potential pathogens or provide incorrect identifications due to non-inclusion in the manufacturer’s database as well as occasions when reporting unusual genera may have the potential to lead to unneeded therapy.
This work will be useful to both users of MALDI or to smaller laboratories that may not find the adoption of MALDI-TOF cost effective and to laboratories that may be considering the purchase of an instrument.
Beija Piedra* and Melissa Walters
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